As a mixed race woman, it is known that white women as victims of crime get more coverage.
But I still think op is being disingenuous. There are other things to be taken into account. They are not 2 exact cases.
Such as Sarah's story was pushed in the press as she was missing. It was pushed by the police in the hope to find her. They were certain she had not gone missing of her own accord and were trying to find her in the hope she was still alive. In this case there wasn't chance to push it as she wasn't ever missing.
Also the fact that Sarah's killer was a serving police officer made it much bigger news.
I saw on TV yesterday there is infact a vigil/protest being organised. Just because one hasn't happened immediately doesn't mean its not happening. Sarah's case was big news because the police had to police the protestors while one of their own was responsible. The protest made news, in part, because of covid and the rules around gatherings.
People seem to ignore one fairly massive point which is really hypocritical. That had both these murders happened outside London, there would be barely any fuss at all. Sarah's case would probably have gone on to become a bigger news story, once the person arrested turned out to be a policeman.
But had he just been a shopkeeper or traffic warden etc, neither would have got big news.
Women go missing and are murdered all the time. Most don't make the news. Especially, outside London.
Eileen Barrot wasn't a big news story. Even though they didn't have the killer in custody.
The 5 women all murdered in South Yorkshire between March and June 2020, didn't make much of a news story either. All white women.
Op is also ignoring status. Had Sarah not been a 'professional' and Sabina not been a primary teacher, I think there would have been even less interest. Had they have been a sex workers or a cleaner, the papers and news channels and society in general would have cares less too.
I do think race plays a part. But there's tons of other factors that the OP is ignoring and placing it all on race. Which I find frustrating because its muddying the waters when tackling race issues.
The focus here, should be on finally doing something about male violence. Not on how much air time 2 different murders in different situations, get.